Safety of implantable pacemakers and cardioverter defibrillators in the magnetic field of a novel remote magnetic navigation system.

INTRODUCTION: Electromagnetic interference with pacemaker and implantable cardioverter defibrillator (ICD) systems may cause temporary or permanent system malfunction of implanted devices. The aim of this study was to evaluate potential interference of a novel magnetic navigation system with implantable rhythm devices. METHODS: A total of 121 devices (77 pacemakers, 44 ICDs) were exposed to an activated NIOBE II® Magnetic Navigation System (Stereotaxis, St. Louis, MO, USA) at the maximal magnetic field strength of 0.1 Tesla and evaluated in vitro with respect to changes in parameter settings of the device, changes of the battery status/detection of elective replacement indication, or alterations of data stored in the device. RESULTS: A total of 115 out of 121 (95%) devices were free of changes in parameter settings, battery status, and internally stored data after repeated exposition to the electromagnetic field of the remote magnetic navigation system. Interference with the magnetic navigation field was observed in 6 pacemakers, resulting in reprogramming to a power-on-reset mode with or without detection of the elective replacement indication in 5 devices and abnormal variance of battery status in one device. All pacemakers could be reprogrammed to the initial modes and the battery status proved to be normal some minutes after the pacemakers had been removed from the magnetic field. CONCLUSION: Interference of a remote magnetic navigation system (at maximal field strength) with pacemakers and ICDs not connected to leads with antitachycardic detection and therapies turned off is rare. Occurring functional abnormalities could be reprogrammed in our sample. An in vitro study will give information about interference of devices connected to leads.

Electrogram-guided substrate ablation with or without pulmonary vein isolation in patients with persistent atrial fibrillation.

AIMS: Ablation of complex fractionated atrial electrograms (CFAEs) is a new approach for the treatment of atrial fibrillation (AF). The purpose of the study was to assess the efficacy of CFAE ablation as a stand-alone strategy in patients with persistent AF and to compare it with a combined approach of CFAE ablation and pulmonary vein isolation (PVI). METHODS AND RESULTS: The study included 77 consecutive patients with persistent AF who underwent radiofrequency (RF) ablation of CFAE as a sole ablation procedure (CFAE group, n = 23 patients) or a combined approach of CFAE ablation and PVI (CFAE plus PVI group, n = 54 patients). Procedures were guided by three-dimensional mapping systems. After the procedure, AF recurrences were evaluated with 7-day Holter recordings at 1, 3, and 6 months and every 6 months thereafter. Treatment failure was defined as >or=1 AF episode lasting >30 s on Holter recordings during follow-up. After a mean follow-up time of 13 +/- 10 months, 2 of 23 patients (9%) with CFAE ablation and 22 of 54 patients (41%) with CFAE plus PVI were in sinus rhythm after a single ablation procedure without anti-arrhythmic medication (P = 0.008). CONCLUSION: Ablation of CFAE as a stand-alone ablation strategy seems insufficient for the treatment of patients with persistent AF. Pulmonary vein isolation plus CFAE ablation significantly increases the mid-term success rate.

Long-term transvenous AV-sequential pacing in a failing atriopulmonary Fontan patient.

UNLABELLED: We report on a 32-year-old man with tricuspid atresia, pulmonary stenosis and hypoplastic right ventricle. He had received a Fontan-Kreutzer procedure (anastomosis between the right atrial appendage and the pulmonary artery) at the age of 14 years. At the age of 2 years, an abdominal VVI-pacemaker with an epicardial ventricular lead had been implanted because of symptomatic third degree AV-block. The patient was now hospitalized with symptoms of severe congestive heart failure. A least invasive approach restoration of AV-synchrony by a dual chamber pacer was performed. Therefore a complete transvenous approach to avoid thoracotomy was attempted. A specially designed CS lead was advanced via the CS to a left lateral ventricular vein for ventricular stimulation. After institution of dual chamber pacing the patient recovered of his heart failure. During a follow-up time of 20 months the patient was clinically stable in the AV-sequential pacing. CONCLUSION: Dual chamber pacing using a transvenously placed coronary sinus lead for ventricular stimulation may improve congestive heart failure in patients after the classic Fontan operation. The minimally invasive transvenous approach might be the best solution for patients who need a pacemaker and are not candidates for surgery or heart transplantation.

Electrical isolation of pulmonary veins in patients with atrial fibrillation: reduction of fluoroscopy exposure and procedure duration by the use of a non-fluoroscopic navigation system (NavX).

AIMS: The aim of the study was to investigate the feasibility of performing segmental pulmonary vein (PV) isolation guided by the NavX (Endocardial Solutions, St Jude Medical, Inc., St Paul, MN, USA) system without the three-dimensional (3D) geometric reconstruction option and whether the use of NavX system will reduce the radiation exposure and procedure duration. METHODS AND RESULTS: The study included 64 patients with symptomatic paroxysmal or permanent atrial fibrillation, in whom PV isolation was performed using fluoroscopic guidance (n=32) or the NavX system (n=32). Pulmonary vein mapping with a circular mapping catheter allowed the identification and localization of myocardial connections between the PV and the left atrium. PV isolation was performed by radiofrequency ablation of these connections at the atrial aspect of the PV ostium. Primary success rate for isolated PVs did not differ significantly in patients ablated under fluoroscopic guidance vs. those ablated under guidance of NavX system [100/107 PVs (93.5%) vs. 120/124 PV (96.8%; P=n.s.)]. Compared with fluoroscopy guided procedures, NavX-guided procedures showed a significant reduction in the fluoroscopy time (75.8+/-24.5 vs. 38.9+/-19.3 min, P<0.05), total X-ray exposure (93.2+/-51.6 vs. 56.6+/-37.9 Gy cm(2), P=0.03), and total procedural time (237.7+/-65.4 vs. 188.6+/-62.7 min, P=0.01). The mean follow-up was 9.5+/-3.0 months. One patient in each group was lost to follow-up. Seven-day Holter monitoring showed that 23 of 31 patients (74.2%) in the NavX-guided group and 21 of 31 patients (67.7%) in the fluoroscopy-guided group were in sinus rhythm (P=0.57). CONCLUSION: The 3D visualization of the catheters by NavX system allows a rapid and precise visualization of the mapping and ablation catheters at the PV ostia and markedly reduces fluoroscopy time, total X-ray exposure, and procedural duration during PV isolation compared with ablation performed under fluoroscopy guidance.

Acute and long-term results of slow pathway ablation in patients with atrioventricular nodal reentrant tachycardia--an analysis of the predictive factors for arrhythmia recurrence.

BACKGROUND: Predictors of atrioventricular nodal reentrant tachycardia (AVNRT) recurrence after radiofrequency ablation including the importance of residual slow pathway conduction are not known. The aim of this study was to report the acute and long-term results of slow pathway ablation in a large series of consecutive patients with AVNRT and to analyze the potential predictors of arrhythmia recurrence with a particular emphasis on the residual slow pathway conduction after ablation. METHODS: The study included 506 consecutive patients with AVNRT (mean age 52.6 +/- 16 years, 315 women) who underwent slow pathway ablation using a combined electrophysiological and anatomical approach. The end point of ablation procedure was noninducibility of the arrhythmia. The primary end point of the study was the recurrence of AVNRT. RESULTS: Acute success was achieved in 500 patients (98.8%). After ablation, 471 patients (93%) were followed up for a mean of 903 +/- 692 days. Of the 465 patients with successful ablation, 24 patients (5.2%) developed AVNRT recurrences during the follow-up. No significant differences in the cumulative rates of AVNRT recurrence were observed in groups with or without electrophysiological evidence of residual slow pathway conduction (P = 0.25, log-rank test). Multivariate analysis identified only age as an independent predictor of AVNRT recurrence (hazard ratio 0.96, 95% confidence interval 0.94-0.99, P = 0.004) with younger patients being at an increased risk for arrhythmia recurrence. CONCLUSIONS: Our study demonstrated that only younger age, but not other clinical or electrophysiological parameters including residual slow pathway conduction predicted an increased risk for AVNRT recurrence after slow pathway radiofrequency ablation.